Leventhal says he has seen the photos that LEOs are circulating of the persons of interest, and that one has a backpack the other a bag. He says there are clear images, multiple images, of the persons of interest.
And that description does match these two.
While these two guys should definitely be checked out, one problem with the scenario involving these two guys is that as you can see here:
http://www.freerepublic.com/focus/news/3008859/posts?page=152#152
...these guys are photographed here at race time 2:35, as you can see by looking at the suspended clock over the street.
The bombing was at about race time 4:05.
Would the bombers really stand around for an hour and a half? Wouldn’t it be more likely the bombers would come in just few minutes beforehand, leave their bombs and get away?
Also, I was pretty sure I heard Rick say they had black bags.
One of the guys here has a blue bag.
Of course, there may have been more than two people involved. Perhaps there were more than two bombs planned, but only two were successfully carried off, and those two involved black bags.